1. Field of the Invention
The present invention relates to a 3-port orthogonal mode transducer, and a receiver and receiving method using the same; and, more particularly, to a 3-port orthogonal mode transducer, and a receiver and a receiving method using the same for receiving a K-band (20 GHz) vertical or horizontal signal transmitted from a satellite as ±45 degree signals through the 3 port orthogonal mode transducer, searching an optimal location by rotating the 3-port orthogonal mode transducer to make the received two signals have the same intensity, and synthesizing the received two signals to output a synthesized signal, so that an optimal satellite signal is received at an optimal location.
This work was supported by the IT R&D program for MIC/IITA [2005-S-301-02, “Development of Satellite Communications System for Communications, Ocean and Meteorological Satellite”].
2. Description of Related Art
In general, a two-way satellite communications system using linear polarization or circular polarization uses different polarizations in transmission and reception.
Thus, a general orthogonal mode transducer (OMT) used for the two-way satellite communications system is a 2-port orthogonal mode transducer in which a transmission port and a reception port are orthogonal to each other.
In the case where a 3-port orthogonal mode transducer is used, a transmission port and a first Rx (Tx1) port receive co-polarization (co-pol), and the transmission port and a second Rx (Rx2) port receive cross-polarization (cross-pol). Since the Rx1 port or the Rx2 port receives a signal from the satellite, a search for which port receives a main beam must be conducted.
A conventional orthogonal mode transducer will now be described in more detail with reference to FIGS. 1A and 1B.
FIG. 1A illustrates a 2-port orthogonal mode transducer including a rectangular transmission port and a rectangular reception port disposed vertically with respect to the transmission port.
FIG. 1B illustrates a conventional 3-port orthogonal mode transducer including a rectangular first Tx (Tx1) port, and a first Rx (Rx1) port and a second Rx (Rx2) port having rectangular shapes and placed vertically and horizontally with respect to the Tx1 port, respectively.
As mentioned above, in the conventional 3-port orthogonal mode transducer, the transmission port and the Rx1 port receive co-polarization, and the transmission port and the Rx2 port receive cross-polarization. Also, the 3-port orthogonal mode transducer receives a signal from a satellite via the Rx1 port and the Rx2 port.
Thus, when a satellite signal is received, it is difficult for the conventional 3-port orthogonal mode transducer to detect an accurate polarization angle for matching between the two reception ports. Particularly, if an Rx signal is weak, a maximum-search method or a minimum-search method for signal reception fails to trace an accurate polarization angle because of error generation.
Also, the conventional 3-port orthogonal mode transducer receives a satellite signal via one reception port in receiving the satellite signal, thereby failing to receive an optimal satellite signal.